The present invention relates generally to surface gauges and particularly to an improved apparatus and method for measuring surfaces to detect irregularities. Still more particularly, this invention relates to apparatus and methods for measuring concrete floors to determine their suitability for use in automated warehouse applications.
In recent years, the concrete floor industry has experienced an increasing demand for extremely flat floors (genericly known as superflat floors) suitable for automated high level warehousing applications. Floor surface height deviations often cause vibrational damage to automated fork and turret trucks traveling upon the floor and reduce the productivity of stacking cranes installed within the warehouse. To meet this increasing demand, the industry is currently attempting to adopt standards and specifications for floor flatness and establish apparatus and methods suitable for measuring floor flatness to ensure compliance with such existing and future standards.
Heretofore, three basic categories of prior art apparatus and methods for measuring floor flatness have been utilized in the art, i.e. manual systems, semi-automatic systems and fully automatic systems.
The manual systems have typically comprised either an engineer's level and rod apparatus or a level straight edge with a sliding dial gauge mounted at right angles to the straight edge. Floor measurements indicated on the rod or from the dial gauge could be obtained and manually plotted. The more recent semi-automatic systems have generally comprised apparatus having a pair of spaced wheels adapted to travel along a selective path of a concrete floor surface and including a sensor adapted to measure the height differential between the two wheels along the concrete floor. Examples of such prior art semi-automatic systems are the Analog Profileograph apparatus manufactured by Edward W. Face Company and an analog measuring appartus manufactured by Mr. Ralph McLean of Fullerton, Calif. Although such prior art manual and semi-automatic measuring systems have proven generally effective in the past, they possess inherent deficiencies which detract from their overall effectiveness and widespread use in the industry.
The foremost deficiency of the manual prior art systems has been the extreme labor intensiveness of conducting measurements, often requiring a pair of skilled surveyors to be maintained upon the job site for prolonged durations. Further, such manual systems although providing a true height reading along the floor surface, have necessitated the accumulation of height readings at only selected locations on the floor surface, with later interpolation of the measurement data to derive a height profile for the entire surface area of the floor. As will be recognized, such interpolation inherently introduces inaccuracies into the measurement results, which in superflat floor applications is oftentimes unacceptable.
The prior art semi-automatic systems, although typically not requiring significant interpolation of data results, have proven to be extremely expensive and, further, have additionally required skilled operating technicians to be utilized upon the job site. Further, such semi-automatic systems have heretofore failed to provide a true height profile of the floor surface, but rather have only yielded a relative height differential throughout the surface area of the floor. In addition, current semi-automatic devices pose many anomalies associated with the data respresentation of absolute surface heights and many such systems have failed to permit the slope or level measurements of the floor to be determined.
A recent semi-automatic sensor beam device comprises a rigid beam supported upon the measurement surface at opposite ends and includes means to permit the rapid leveling of the beam into a level horizontal plane or axis. A height sensor is carried for transport along the beam and is adapted to contact the measurement surface. The sensor and transport mechanism generate height and position signals which may be processed by a microprocessor and printed or plotted to yield a true height profile of the measurement surface throughout the length of the beam.
A recent automatic single axis transport trolley device comprises the use of a trolley having a pair of wheels adapted to contact and travel upon the surface to be measured. A pair of optical sensors are mounted upon servo units attached adjacent each of the contact wheels and are adapted to track an optical beam utilized to generate a reference plane, axis or datum. During travel of the trolley along the surface, variations in the surface height from the optical reference plane are detected by the optical sensors which output signals that may be similarly processed to print and plot the true height profile of the measured surface.
A recent automatic dual axis transport trolley apparatus comprises a trolley which may be transported along the length of the surface to be measured and basically combines the structure of the semi-automatic beam sensor and fully automatic single axis embodiments to permit in a step and repeat fashion, simultaneous sensing, printing, and plotting of the true surface height profile along both a transverse and longitudinal coordinate axis.
However, the recent devices, while providing satisfactory results are excessively expensive for many applications. In other applications optical beam systems lack sufficient precision to determine whether a floor meets flatness specifications.
Thus, there exists a substantial need in the art for an improved measurement apparatus and method for measuring surface heights which automatically provides accurate, true height profile and slope data for concrete floor surfaces without the need of utilizing skilled labor.